The lines with equations:
y = x + 1,
y = mx − 1,
& y = −4x + 2m
pass through the same point.
Determine all possible values for m.
This is really just a system of three equations in 3 unknowns.
Equate the first and second and solve for x:
Equate the first and third and solve for x:
Equate these two and solve for m:
0=m^2 - 3m - 9
The solutions are
m=-3/2 or m=3
The corresponding intersection points are (-4/5,1/5) & (1,2) respectively.
Graphing the equations in the xy plane with m an animated parameter is interesting to watch. One line stays still, one slides up or down, one tilts to meet them on either side.
Posted by Jer
on 2018-01-07 12:29:31